Handbook of Research on Wireless Multimedia: Quality of Service and Solutions

Handbook of Research on Wireless Multimedia: Quality of Service and Solutions

Nicola Cranley (Dublin Institute of Technology, Ireland) and Liam Murphy (University College Dublin, Ireland)
Indexed In: SCOPUS
Release Date: July, 2008|Copyright: © 2009 |Pages: 544
ISBN13: 9781599048208|ISBN10: 1599048205|EISBN13: 9781599048239|DOI: 10.4018/978-1-59904-820-8


The recent rapid advances in wireless technologies have created a demand for high quality multimedia applications and services. These advanced multimedia applications give rise to a new set of challenges in providing Quality of Service (QoS) when delivering these services over wireless networks.

Handbook of Research on Wireless Multimedia: Quality of Service and Solutions highlights and discusses the underlying QoS issues that arise in the delivery of real-time multimedia services over wireless networks. This cutting-edge book presents state-of-the-art solutions from leading researchers active in the field to address the QoS issues for different wireless multimedia applications.

Topics Covered

The many academic areas covered in this publication include, but are not limited to:

  • Broadband satellite
  • Buffer control techniques
  • MANETs
  • Mobile Devices
  • NGN environment
  • QoS
  • Radio Resource Management
  • Resource Management
  • Streaming
  • Transport protocols
  • Video services
  • VoIP
  • Wireless multimedia
  • Wireless network
  • WLAN

Reviews and Testimonials

I believe Wireless Multimedia: Quality of Service and Solutions will stand out as a long lasting reference book in the field of mobile multimedia for many years to come

– Abbas Jamalipour, Fellow IEEE Sydney, Australia

This book presents state of the art research that tackles the challenges of providing QoS for multimedia services of wireless technologies.

– Nicola Cranley, Dublin Institute of Technology, Ireland

Cradley and Murphy present recent research into the provision of quality of service for multimedia services of wireless technologies.

– Book News Inc. (December 2008)

Table of Contents and List of Contributors

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Abbas Jamalipour, Fellow IEEE Sydney, Australia

In the past two decades we have witnessed tremendous advances in wireless technologies, in particular those aimed at personal and mobile communications using cellular and ad hoc configurations. Cellular mobile communication, considered a luxury in the early 1990’s, has become one of the everyday necessities for hundreds of millions of people all around the world in less than twenty years. Applications have changed dramatically from simple voice telephony to a wide range of multimedia applications. Exponential advancement in VLSI technology and liquid crystal display at the same time provided telecommunications engineers with an unbelievable electronic gadget in people’s pockets. Ubiquitous communications has therefore become a reality and an all-in-one device is no longer a dream. Television broadcasting has found a new direction through the digital era, from large wall-mounted displays to the smaller and more private displays of mobile phones.

Wireless communications has had to develop at the same pace as its hardware and software counterparts in mobile devices so that they can be connected to content providers over the Internet and the telecommunications backbones. New wireless technologies have been added to the single cellular air interface mobile phones. These days we see smart phones with several air interfaces, all built on a tiny chip. They can connect simultaneously to wireless local area networks; second generation networks such as GSM and GPRS; third generation networks like UMTS; and Bluetooth, in multiple frequency spectra. Those devices sometimes even come with their own satellite navigation system, which can locate the device and provide further information to users. With the inclusion of Windows-based operating systems on mobile devices, the user device is no longer just a phone but a handy personal computer with the usual myriad applications.

With all these advances, mobile multimedia is in our hands and the important issue is how the service quality can be maintained at a level similar to what we had in the past and which users have come to expect. The topic of mobile multimedia quality of service therefore remains the most important issue to be dealt with by telecommunications engineers.

In the past ten years we have seen many works in the literature on the topic of quality of service in mobile environment. Dr. Nicola Cranley and Prof. Liam Murphy have put together an excellent edition of chapters, carefully chosen, reviewed, and edited in their book covering the technical solutions to this problem. They break down the problem nicely into three parts: network layer, application layer, and end-user layer, which can serve as the main elements in providing end-to-end quality of service to mobile multimedia applications. As quality of service provisioning requires good cooperation among communication layers and is not achievable by individual layer’s attempts, the last part of the book addresses cross-layer solutions to the problem.

Nicola and Liam have selected a wide range of experts from all over the world to detail the problems and possible solutions in this harmonized edition. The book, while written by many authors, is read as a single piece of work with a focused and understandable theme right throughout the entire edition. I believe Wireless Multimedia: Quality of Service and Solutions will stand out as a long lasting reference book in the field of mobile multimedia for many years to come. I am confident that the tutorials and research works presented in this book will further seed new research topics in the field for a better and more efficient use of hardware and software advancements to achieve mobile multimedia communications into the future.


The rapid advances in wireless technologies have brought about a demand for high quality multimedia applications and services such as video telephony, multimedia streaming, video games, audio streaming e.g. podcasting, IP HDTV broadcasting and voice over IP. These advanced multimedia services bring a new set of challenges for providing Quality of Service (QoS) for delivering these services over wireless networks.

Wireless technologies are becoming increasingly sophisticated and efficient enabling support for higher bit rates. However, high and variable error rates and delays in wireless systems are still significant obstacles for providing QoS support for multimedia applications, especially when such variations occur on short timescales with respect to the applications being supported. Multimedia applications, in particular, impose significant resource requirements on bandwidth constrained wireless networks. Under these conditions it is difficult to provide any QoS guarantees. In particular the delay constraints associated with real-time multimedia pose the greatest challenge. Real-time multimedia is particularly sensitive to delay, as multimedia packets require a strict bounded end-to-end delay, i.e. every multimedia packet must arrive at the client device before its playout time with enough time to decode and display the contents of the packet. If the multimedia packet does not arrive on time, the packet is effectively lost and this affects the end-user perceived quality.

QoS is a crucial part of wireless multimedia design and delivery. Poor QoS results in poor service uptake by users which will result in the potential offered by recent advances in wireless and multimedia technologies not fully utilized. There are many aspects to QoS provisioning. These include Network-layer QoS, Application-layer QoS and ultimately End-user QoS. Network-layer QoS is concerned with the reliable and fast delivery of multimedia data over the wireless technologies. Many new and emerging wireless technologies such as IEEE 802.11e have been designed and developed with integrated QoS enabling controls. However these controls need to be configured and optimized in order to provide Application-layer QoS. Application-layer QoS on the other hand is concerned with the quality of the multimedia encoding, delivery, adaptation, decoding and play out on the client device. End-user QoS is concerned with the end-user experience in terms of audio and visual quality.

Typically these QoS layers are treated independently and in isolation yet the QoS schemes implemented at each of these layers have an effect on each other. It is essential for network managers, engineers and application developers to have an understanding of the QoS schemes that are in place at the network, application and end-user layer in order to be able to provide a fully end-to-end QoS solution. The ultimate goal of these QoS schemes is to maximize end-user QoS. With such diversity of QoS issues for multimedia and wireless technologies, there is an opportunity for novel QoS techniques to be developed at all layers.

Objectives and Structure of this Book
The objective of this book is to present state of the art research that tackles the challenges of providing QoS for multimedia services of wireless technologies. There are many aspects to QoS provisioning. We have identified three key layers for QoS provisioning. These include Network-layer QoS, Application-layer QoS and ultimately End-user QoS. We have structured this book to represent the latest state of the art research in each of these three layers and have also included a section that covers Cross-layered solutions which touch two or more of these QoS layers.

This book is intended to:

  • Identify each of these different layers of QoS and highlight the underlying QoS issues that arise and affect the performance of multimedia applications over wireless networks.
  • Present the QoS issues that arise with different types of multimedia applications and services over different types of wireless technologies.
  • Present novel solutions and state of the art research that has been done to address QoS issues for different wireless multimedia applications.

    The first section of this book deals with the Network-layer QoS. The primary characteristic of next generation wireless and mobile communication systems is heterogeneity, for example, wireless cellular networks, wireless local area networks, wireless personal area networks. It is crucial for inter-operability and seamless roaming among these different networks. Wireless technologies have a finite bandwidth capacity and are error prone media, it is important for wireless networks employ radio resource management schemes and optimised QoS handling to satisfy and meet the needs of users of multimedia services.

    With the development of multimedia compression and coding technologies, more and more real-time applications, such as video and audio, and the proliferation of pervasive devices create a new demand for wireless multimedia communication systems. Multimedia services can be optimised and adapted to the challenges of wireless devices and service delivery. The second section deals with Application-layer QoS. This encompasses quality-aware multimedia encoding, delivery, adaptation, decoding and buffering on the client device.

    The third section of this book deals with end-user QoS. End-user QoS is concerned with the end-user experience in terms of audio and visual quality. Traditionally, a reactive approach has been adopted for engineering QoS for multimedia streaming applications. The main problem with this approach is that a poorly designed system cannot be tuned to perform as well as a system that was well designed from the outset. By integrating end-user QoS into the design of multimedia streaming systems, a more proactive approach can be adopted for the development and delivery of multimedia services over wireless networks.

    Finally, the last section of this book presents Cross-layer QoS solutions. Cross-layered solutions are extremely difficult since they rely on optimising QoS at two or more layers of the multimedia system, increasing the complexity of the optimisation; but also providing greater flexibility and potential to appropriately tune the network, application, and end-user layer to achieve the desired QoS.

    Network QoS
    With the recent advances in microelectronics, mobile devices now come equipped with a range of different wireless technologies on the one device. For example many PDA devices now come equipped with WLAN, 2.5G/3G cellular, Bluetooth and Infrared. Often different wireless networks co-exist allowing users to switch between different wireless technologies. Switching between different wireless technologies is an important and difficult challenge since they have different physical layer, link layer and MAC layer schemes which result in a large variation in bandwidth and end-to-end delays making seamless transitions between different wireless technologies and continuous QoS difficult.

    There are many performance-related issues associated with the delivery multimedia applications over wireless networks. Among the most significant are finite bandwidth resources, high channel error rates, contention between users for access to bandwidth, collisions, signal attenuation with distance, signal interference, etc. There are a number of techniques that have been developed and integrated into wireless technologies in order to facilitate the provisioning of network-layer QoS. The most well-known mechanisms are the Integrated Services (IntServ) and the Differentiated Services (DiffServ). Different wireless technologies such as General Packet Radio Service (GPRS)/Universal Mobile Telecommunications System (UMTS) and IEEE 802.11e have very different mechanisms for QoS support. Resource management schemes and admission control schemes can be used to prevent the network becoming overloaded such that poor network performance begins to negatively affect the multimedia applications.

    In Chapter 1, Skehill et al describe how QoS can be provided in multi-access networks in particular UMTS and 802.11 networks. They demonstrate the new network management challenges and QoS provisioning problems posed by heterogeneous networks. To address this challenge they present their work on joint admission control strategies that can be employed to provide QoS. They demonstrate their system on an advanced test platform that replicates an integrated Release 4 UMTS network and standard IEEE 802.11b network. Their results show that by tightly coupling UMTS and WLAN technologies, the end user enjoys a higher level of Quality of Service.

    In Chapter 2, Staehle and Mäder describe High Speed Downlink Packet Access (HSDPA), and provide some insights into the Radio Resource Management of integrated UMTS/HSDPA networks. The development of HSDPA was initiated as response to an increasing demand for high-speed mobile Internet access. HSDPA enables data rates of several Megabits per seconds with packet latencies under 100ms. This Chapter covers aspects of Radio Resource Management specific to HSDPA such as channel-aware scheduling and radio resource sharing strategies, and analyses the impact of Radio Resource Management on the achievable Quality of Service.

    With pervasive and diverse wireless networks, users roam and move between heterogeneous networks. In Chapter 3, Nasser and Bejaoui describe the challenges for next generation of wireless networks to provide seamless mobility across heterogeneous wireless networks and QoS provisioning to support multimedia services. They describe how 4G wireless technologies offer great potential to meet the challenges posed by multimedia services and change the way mobile devices are used and can be adapted to provide a wide variety of new multimedia applications. One of the key challenges in heterogeneous network environments is the ability to control and manage handoffs. Nasser et al. describe their solution using Artificial Neural Networks (ANNs) to identify the best existing wireless network that matches predefined user preferences set on a mobile device when performing a vertical handoff.

    Multimedia applications are bandwidth hungry and resource demanding services. Providing multimedia services over bandwidth constrained wireless networks is challenging. In Chapter 4, Li et al provide a rich and comprehensive overview of the architectures, algorithms, and protocols that are employed as radio resource management in IEEE 802.11 based wireless networks, mobile ad hoc networks, and wireless mesh networks. Li and Riggio demonstrate that with a successful resource management strategy, bandwidth usage can be minimized whilst providing maximized QoS and end-user QoS for multimedia applications.

    Application QoS
    There are several aspects to Application-layer QoS that deal with all stages of the applications lifecycle including encoding, delivery, adaptation, decoding, error correction and error concealment. Before multimedia can be streamed over the network, the multimedia content is encoded and prepared for transmission. The choice of the right encoding settings is crucial for the performance of the delivery of the multimedia stream over the network. For audio, voice and video content, there are a number of different encoding schemes and encoding configuration parameters that can be used to optimally encode the multimedia content which has an affect on the network-layer QoS requirements of the multimedia stream. When the content is ready to be delivered over the network, the encoded multimedia data is packetised with an optimal number of samples contained in each packet.

    However when the network is overloaded and congested, its ability to reliably deliver the multimedia packets within the strict delay constraints is reduced. Such delays can result in packets being lost at the client device since they arrived too late to meet the network-layer QoS delay requirements. Packets can also be lost due to errors over the wireless channel. The loss of multimedia data in the network has a significant impact on the end-user perceived QoS. To overcome this, many multimedia streaming systems have adaptation capabilities whereby the offered multimedia content is adapted in a seamless and imperceptible manner in order to minimize the unwanted negative effects of poor network conditions on the multimedia stream. On the client device, the multimedia player application has a number of techniques to recover any errors or losses in the received stream. Error correction and error concealment algorithms interpolate the missing multimedia data from the received data in order and mask these errors to improve the end-user perceived quality in spite of these losses.

    With the proliferation of WLAN technology, and the explosive growth of VoIP services, Chapter 5 by Sfairopoulou et al describes their work for delivering high quality VoIP services over 802.11 networks. They describe how voice codecs can be optimised and adapted to the network conditions in order to provide the best QoS, for example, through the use of multi-rate voice codecs and link adaptation. They present a novel solution to the multi-rate and codec selection mechanism which maintains the end-to-end delay and packet loss values within acceptable levels and provide the desired QoS for the voice flows.

    Chapter 6 by Markou and Panayiotou describes how network buffer control techniques can be used as a means to provide QoS. Although this solution has been applied to wired networks, with the explosive growth of wireless access technologies and the challenges posed by multimedia applications, buffer control schemes have had to significantly adapt to the characteristics wireless networks. This chapter presents a new methodology for automatically adapting the various buffer thresholds such that the network exhibits optimal or near optimal performance even as network conditions change making it ideal for wireless multimedia service delivery.

    With the large number of wireless devices and their growing capabilities, power consumption and battery lifetimes are still significant obstacles in the continuous seamless play out of multimedia services on such devices. In Chapter 7, Muntean and Adams consider the power consumption problems presented by WLAN enabled mobile devices. Decoding and playout of multimedia services adds to the processing overhead causing it to discharge faster. In this chapter, Adams and Muntean describe an Adaptive Buffer Power Save Mechanism (AB-PSM) that enables an increase in battery lifetime during mobile multimedia streaming which in turn increases the end-user QoS.

    In Chapter 8, Jodra et al describe the new application scenarios for mobile ad hoc networks, including multimedia services and/or on-line games. They discuss how the demand for such wireless connectivity requires certain levels of quality of service. For this reason a large effort has been carried out by both the industry and research community towards QoS provisioning in MANETs. However, when analysing QoS aspects in MANETs the first thing to notice is that MANETs’ special characteristics prevent the use of traditional QoS mechanisms in these environments. These particularities are related not only to the wireless transmission medium itself (which is shared with other kinds of wireless networks) but also to the uncertainty derived from the mobility of the nodes and subsequent network topology variations.

    Hence, major challenges to be faced while defining QoS mechanisms for MANETs include the wireless channel, multihop nature of communications, node mobility, lack of centralised control, dynamic network topology and limited device resources. These challenges result into a series of constraints to be added to QoS traditional ones (namely bandwidth, delay or jitter), such as battery power, CPU usage and stability of the routes. Most of these constraints demand different QoS mechanisms in different protocol layers, ranging from physical layer and MAC contention mechanisms to application level. However, since MANETs particularities are related to network topologies most of the efforts analysed aimed at developing routing strategies focused on dealing with dynamic topology problems.

    End-user QoS
    End-user QoS is the primary goal of application-layer QoS schemes and a somewhat secondary goal of network-layer QoS schemes. Measuring end-user QoS is an extremely complicated task which draws from many knowledge domains such as psychology, cognitive science and signal analysis. There are two key methods for assessing end-user QoS; the first is through subjective assessment and testing, while the second is through the use of objective metrics. Different objective metrics exist for audio, video and voice quality analysis. The main goal of objective metrics is to measure the perceived quality of a given audio or visual signal. There are many factors that affect how users perceive quality, such as audio loudness, lip synchronization, video content, viewing distance, display size, resolution, brightness, contrast, sharpness/fidelity, and color. However, it is only through the accurate measurement of end-user QoS, that QoS schemes can be developed and optimised.

    In Chapter 9, Kos et al present a service-aware policy based approach to Next Generation Networks (NGN) quality assurance, considering both perceptual quality of experience and technology-dependent Quality of Service issues. The nature of the NGN environment presents several complex issues regarding quality assurance not faced in legacy environments, such as the multi-network, multi-vendor and multi-operator IP-based telecommunications environment, distributed intelligence, third-party provisioning, and fixed-wireless access. The existence of multiple separately operated and interconnected domains requires intelligent interconnection mechanisms. On the other hand, real-time personalized interactive multimedia NGN services require end-to-end quality assurance regardless of the traversed domains. Meeting these two requirements is a complex task and involves careful quality-related planning in each separate domain and coordination of these on a service-aware end-to-end basis.

    In Chapter 10, Zapater and Bressan discuss the quality assurance of multimedia services over IP networks from the end user standpoint, and describe the concept of Quality of Experience (QoE). The focus is on video services that can be considered a significant evolution of services providers’ portfolio. Traditional quality management approaches adopted by service providers are mostly focused on the network perspective rather than the user perspective. The authors present quality requirements for video and TV services, and performance measures that focus on the quality perceived by the end user. This QoE approach is broader than one based on Quality of Service (QoS), since it takes into account how well a service meets customer goals and expectations rather than focusing only on network performance.

    Chapter 11 by Picovici and Nelson describes the latest work for measuring perceptual voice quality and their application to wireless networks. They provide a review of various subjective testing methodologies and objective voice quality measures describing the target application of this metric and the performance limitations. They present the three main categories of objective voice quality measures, signal-based models, network-based (planning) models and both intrusive and single-ended monitoring based models. They have a devised a technique based on call history that can be used to predict end-user QoS for VoIP calls.

    In Chapter 12, Serif and Ghinea investigate user experiences of accessing streamed multimedia content. Through the creation of pre-defined QoS transmission profiles, the end-user experience is enhanced. These pre-defined profiles have built-in perceptual information and are based on both static (such as device type, CPU speed, and display specifications) and dynamic parameters (such as streamed content type location of the device/user, context of the device/user). From their work, end-user perceived QoS could be maintained whilst requiring fewer network resources.

    Chapter 13 by Koumaras et al treats Perceptual QoS (PQoS) assessment methods for multimedia applications and services. In this chapter they describe subjective quality assessment methodologies and review the latest PQoS assessment models for multimedia services. Through their work they present novel PQoS prediction models for web, video, VoIP and on-line gaming services. Their PQoS prediction model can be used to for the development and monitoring of PQoS-aware multimedia devices and networks for live multimedia services.

    Cross-Layered Solutions
    Emerging wideband code division multiple access (WCDMA) data services will probably require resource allocation to ensure that throughput targets are met, and may employ scheduling and access control to achieve this. In Chapter 14, Zhang and Jordan introduce a two-layer scheduler and connection access controller that attempts to balance efficiency with fairness. Their scheduler takes advantage of variations in the wireless channel, and they propose an algorithm that offers targeted throughput for interactive nomadic data streams, by integrating connection access control and resource allocation per connection request with rate scheduling on a per frame basis adaptive to slow fading. Upon the request of a data stream connection, a target throughput is negotiated between the user and the network/base station. The network attempts to achieve the throughput targets over the duration of each individual connection by maximizing a system objective based on users’ satisfaction as represented by a utility function.

    There is an increasing need for broadband communications anytime, anywhere for users that expect to receive multimedia services with support of quality of service. In Chapter 15, Chini et al describe the satellite option to bridge the digital divide in those areas where terrestrial solutions are infeasible or too expensive. They provide a survey of the ETSI standardization framework for satellite networks, and describe resource management schemes for both the forward and return link. Finally they present a case study on the integration of a DVB-S/DVB-RCS satellite system interconnected with a WiFi segment for local coverage.

    Hybrid schemes make use the QoS-enabling features at various layers of the wireless multimedia service chain and optimise the QoS of the service using a cross-layer approach. Chapter 16 by Papadimitriou and Tsaoussidis presents a network and end-user QoS cross-layer approach for multimedia streaming services. In this chapter they assess the efficiency of transport-layer solutions for multimedia traffic in heterogeneous networks. They compare the multimedia application requirements against the QoS features provided by the underlying network and present methods to measure the perceptual QoS assessment for the voice and video streams.

    In Chapter 17, Bejaoui and Nasser provide a cross layer design for resource allocation over multimedia wireless networks. In this chapter they show how inter-layer dependencies can bring QoS improvements and the performance gains for real-time and non-real-time applications. This chapter concentrates on the Packet Scheduling and Admission Control Schemes proposed for QoS provisioning for multimedia services over next generation wireless networks. In particular this chapter focuses on the radio channel conditions and explore the novel approaches based on cross-layered radio resource management protocol.

    The reliable transmission of multimedia services over bandwidth constrained error prone wireless networks is critical. In Chapter 18, Gur et al describe the fundamental issues at the transport layer affecting the provision of QoS for wireless multimedia applications. They describe how the traditional transport layer protocols must be adapted to meet the challenges of delivering multimedia applications over best-effort wireless networks. They describe the latest trends and cross-layer solutions that rely on interaction between the different protocol layers. They show that cross layer protocol solution presents many challenges since such cross-layer schemes increase the inter-layer dependencies calling for a more complex protocol design, and present stability issues.

    QoS is an important factor in the design and development of wireless multimedia applications and services. Different multimedia applications have very diverse QoS requirements in terms of bit rates, delay constraints, and loss tolerances. In a wireless environment, users are mobile and move between wireless technologies where the available resources are scarce and dynamically change over time. To complicate matters further, there is dramatic heterogeneity among end user devices in terms of latency, video visual quality, processing capabilities, power, and bandwidth. Providing QoS with both network and device heterogeneity to achieve efficiency in network bandwidth is a significant challenge. In this book we shall look at the major issues and challenges surrounding the provision of QoS for multimedia applications over wireless networks.

    Author(s)/Editor(s) Biography

    Nicola Cranley received her B.Sc. in Applied Physics with French from Dublin City University in 1998, M.Sc. in Computing for Commerce and Industry from the Open University in 2004, and a Ph.D. in Computer Science from University College Dublin in 2004. Dr. Cranley has published over 25 refereed journal and conference papers in the areas of video quality analysis, QoS for multimedia streaming and wireless multimedia. Her research interests include wireless video streaming, video adaptation and wireless networks.
    Liam Murphy received a B.E. in Electrical Engineering from University College Dublin in 1985, and M.Sc. and Ph.D. in Electrical Engineering and Computer Sciences from the University of California, Berkeley in 1988 and 1992 respectively. He is currently an Associate Professor in Computer Science at University College Dublin, where he is Director of the Performance Engineering Laboratory. Prof. Murphy has published over 100 refereed journal and conference papers on various topics, including multimedia transmissions, dynamic and adaptive resource allocation algorithms, and software development. His current research projects involve mobile and wireless systems, computer network convergence issues, and web services performance issues. Prof. Murphy is a Member of the IEEE and a Fellow of the Irish Computer Society.


    Editorial Board

  • Gavin Dudeney, The Consultants-E, Spain
  • Clarissa Jordão
  • Terry Kidd, University of Texas, USA
  • Piet Kommers, University of Twente, The Netherlands
  • Jeannette Littlemore, University of Birmingham, UK
  • Steve Mann, University of Warwick, UK
  • Vera Menezes, Universidade Federal de Minas Gerais, Brazil
  • Peppi Taalas, University of Jyväskylä, Finland
  • Jacques Viens, Université de Montréal, Canada
  • Panayiotis Zaphiris, City University London, UK
  • Felicia Zhang, University of Canberra, Australia